Coping with human CO_2 emissions

摘要

For two centuries, a natural experiment has been showing how increasing atmospheric CO_2 affects plants. Laboratory work provides pointers as to how they will respond in the future. The industrial revolution in the western world had enormous socioeconomic effects — but it also unwittingly started a global experiment that has now been running for two centuries. One of the unforeseen consequences of the industrial revolution was a steady increase in the amount of carbon dioxide in the atmosphere. Plants responded by having fewer stomata—paired 'guard' cells, found mainly on the surface of leaves, that control the uptake and release of gases. Enrichment of atmospheric CO_2 continues. But how will plants respond in the future? Water loss and CO_2 uptake occur primarily through the stomata, so a drastic further decrease in their numbers would impair processes such as transpiration and photosynthesis.